Radio Broadcast (May 1928-Apr 1929)

214 RADIO BROADCAST AUGUST, 1928 A WAVEMETER — OLD STYLE A bit of history. This old time wavemeter was used by Phelps at pzT in Minneapolis in the fall of ign . The range is from 10 to 1 50 meters, (a range of 28,000 kc) and the condenser has a capacity of 1000 mmfds. detection set built before breakfast in some miraculous way by Douglas. With this nothing was heard at Newton — 180 miles west — at night, which was expected. At Grand Canyon, Arizona, both Norwell Douglas (Kansas) and Phelps (New York) were very weak. At San Diego, neither were the signals thrillingly loud nor were they amazingly steady, but they were there ! At San Antonio, in the midst of perfect receiving conditions, there was an equally perfect silence. As nearly as can be established, the reflector at qeht (the Kansas station) was not aimed right, and the schedule at 2EB (the New York station) was either not sent or else sent at another time than it was listened for. At New Orleans the set stubbornly refused to function and after finally being persuaded into unstable oscillation, grudgingly turned out a rather weak and barely readable signal from Kansas. All this looked highly encouraging, especially when viewed in the light of the reception of Italian ier (Santangeli) — a distance of about 1000 miles — at Tripolitania by Captain Filipini, and the rather consistent 24 mile reception by C. H. West (2CSM)'of his own very low-powered automatic signals at distances within 24 miles of Stapleton, New York, and finally the very nice work of C. H. Turner with a crystalcontrolled 5-meter transmitter in the Vermont mountains at distances above 100 miles. The thing was especially interesting because the results did not "gee" very well. Turner's conclusions were that the wave was a daylight one (on which we seem to agree) and that it was useful only for straight-line work, whereas we have numerous cases wherein the signals were very healthy indeed behind hills of good size, for instance, on the opposite side of Avon "mountain" (Connecticut for hill) from my own Hartford station. Again the alleged daylight wave has at certain times shown a strange disposition toward abnormally strong signals on very foggy days, though this applies seemingly to the " local" (60 miles or less) signal only. In the main, the distance reception has been best and steadiest with clear skies, the California "high fog" (West Coast for generally cloudy) being a good barrier in the few cases where it was possible to observe while it parted. Again, the attenuation (i.e., the dying off of the signal as one goes from the station) does not seem to follow theory. The thing seems to fall off no worse than some other wavelengths which are, theoretically speaking, better. THE ABSENT ANTIPODES |T IS, perhaps, especially interesting that the 1 Australian observers, who seem to be better than average, have never heard the signals. They are the ones with the best mathematical right to hear signals — which again leaves matters open for speculation. For that matter there is no end of room for speculation in the whole thing. A few of the puzzling things we hope to answer. Douglas has a pair of reflectors, horizontal and vertical, with which to aim signals at suspected points, and Langreth of Wesleyan University, at Middletown, Connecticut, is building a crystalcontrolled 5-meter transmitter to wash out some of the other uncertainties. To fit into this picture there is being made a receiver with cx-322 intermediate-frequency amplification, a longwave heterodyne and an autodyne first detector, all of which is hoped to be an improvement on present equipment. Perhaps there will be something more to report of communication results. Meanwhile, the reader, if still following this story, has begun to do a bit of speculating of his own, asking of what conceivable use all this may be. As to that — why is that so serious? If we make a "useful'' wave of 5 meters then the utilitarians will say the thing has been good all along. And if by any rare chance an interesting scientific fact emerges we have the approval of the pure scientist. On the other hand, if neither follows, our plaything is still good as a plaything and should have the whole-hearted approval of the radio amateur. Nor are we at all a closed corporation; if anyone in any of these classes desires to play the game with us — welcome! More about this will be said in a following issue. A WAVEMETER — NEW STYLE A later chapter in the story. The new short-wave meter at 2EB, Phelps' present station. The condenser capacity is 33 mmfds. there are 5 plates instead of 43, and the tuning range is from p.p to 10.8 meters (30,301 kc. to 27,77s kc., or 2525 kc.) for the full scale of the short-wave coil. This gives a precision, aside from the mechanical improvement, of approximately 14 times that of the old wavemeter! The one-turn coil is for ymeter work